Invention of the Photoresistor and phototransistor

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gain wire

gain wire

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Joined 2004
#1
OK, I got a good question for the electronics people here. I'm talking the old guys (and I mean that with no disrespect, as I appreciate everything that is old): What year was the photoresistor invented
Also, what year did the phototransistor come out? And by this I mean commercially available. My guess on photoransistors is 1965.. But that's just a guess...

I would have posted this question in the electronics forum but it seems it has vanished..

Thank you!
 
#2
ALL the old germanium transistors were light sensitive.

I used OC 44s and '45s as phototransistors by scraping the black paint off.
Some were filled with an opaque material (just repainted the black), some were filled with clear translucent stuff which were the ones to use.

Mullard did produce a phototransistor at the time.
I believe it was a 44/45 with no paint and clear filling but cost a shedload more!


Andy


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#4
gain-wire said:
OK, I got a good question for the electronics people here. I'm talking the old guys (and I mean that with no disrespect, as I appreciate everything that is old): What year was the photoresistor invented
Also, what year did the phototransistor come out? And by this I mean commercially available. My guess on photoransistors is 1965.. But that's just a guess...

I would have posted this question in the electronics forum but it seems it has vanished..

Thank you!
Click to expand...

I have some FPT-100's datecoded 1968 and they were cheap already then.
 
#5
Some golden oldies here 🙂
I remember the OCP71, the photo version of the OC71 and the ORP12 ? cadmium sulphide photo resistor.
Back to OC transistors, wasn't that a possible cause of hum, if the black coating was damaged and you had fluorescent lights etc.
 

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#9
Ah, OK. well I was looking more for original devices, semiconductors that were designed with the window there. I'd like to get some part numbers like the FPT-100, (thank you scott wurcer) and possibly obtain some if anyone has any...

thank you all
 
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